Landslide hazard and risk: an integrated management of...

University of Milan-Bicocca

Department of Environmental SciencesLandslide hazard and risk: an integrated management of environmental systems

LANDSLIDE PROCESSES: FROM GEOMORPHOLOGIC MAPPING TO DYNAMIC MODELLING6-7 FEBRUARY 2009 Strasbourg, France

Angelo Cavallin

Dipartimento di Scienze dell’Ambiente e del Territorio, Università degli Studi di Milano-Bicocca, Milano

Landslide hazard and risk: an integrated management of

environmental systems




RISK SYSTEM

HAZARD

VULNERABILITY

VALUE

RISK

NATURAL

PROCESSES

HUMAN

ACTIVITIES

PREDISPOSINGFACTORS

TRIGGERINGFACTORS

SUSCEPTIBILITY

RETURN PERIOD, FREQUENCY

SPA

CE

TIM

E

ECONOMIC

SOCIAL

STRUCTURES

INFRASTRUCTURES

PEOPLE

DIRECTINDIRECT

MAGNITUDERUNOFF

LANDSLIDE RISK




(Cavallin, Panizza, Marchetti, Soldati, Geomorpholgy, 1994)




RISK SYSTEM

HAZARD

VULNERABILITY

VALUE

RISK

NATURAL

PROCESSES

HUMAN

ACTIVITIES

PREDISPOSINGFACTORS

TRIGGERINGFACTORS

SUSCEPTIBILITY


SPA

CE

TIM

E

ECONOMIC

SOCIAL

STRUCTURES

INFRASTRUCTURES

PEOPLE

DIRECTINDIRECT

MAGNITUDERUNOFF

LANDSLIDE RISK ASSESSEMENT

Black box ?

Grey box ?

White box ?




Gravity is the primary factor in a landslide. Soil on a flat surface does not move. On a slope, gravity alone also may not trigger a landslide. But when another disrupting factor -- like rain -- comes into play, gravity will pull sediment downhill.

Predisposing factors Triggering factors

landslides

LANDSLIDES: A NATURAL PROCESS




NATURAL

PROCESSES

PREDISPOSINGFACTORS

TRIGGERINGFACTORS

SPA

CE

TIM

E




PREDISPOSING FACTORS

Geological causes•Weak materials

•Sensitive materials

•Weathered materials

•Sheared materials

•Jointed or fissured materials

•Adversely orientated discontinuities

•Permeability contrasts

•Material contrasts

Morphological causes•Slope angle

•Uplift

•Rebound

•Fluvial erosion

•Wave erosion

•Glacial erosion

•Erosion of lateral margins

•Subterranean erosion

•Slope loading

•Vegetation change

NATURAL




•Intense rainfall

•Earthquake

•Volcanic eruption

•Rapid snow melt

•Prolonged precipitation

•Rapid drawdown

•Thawing

•Freeze-thaw

•Shrink-swell

•Ground water changes

•Soil pore water pressure

•Surface runoff

•Seismic activity

NATURAL TRIGGERING FACTORS




LANDSLIDES AS RISK.

LANDSLIDES CAN BE A RISK IF THEY AFFECT VULNERABLE HUMAN ACTIVITIES WITH AN INTENSITY AND A MAGNITUDE (HAZARD) WHICH PRODUCE DAMAGE WITH A SOCIAL ECONOMIC VALUE




• VALUE meaning the expected degree of loss due to a particular natural phenomenon and as a function of both natural hazard and vulnerability.

•NATURAL HAZARD meaning the probability of occurrence, within a specific period of time in a given area, of a potentially damaging natural phenomenon. •

•VULNERABILITY meaning the degree of loss to a given element at risk or set of such elements resulting from the occurrence of a natural phenomenon of a given magnitude and expressed on a scale from 0 (no damage) to 1 (total loss).

• RISK meaning the expected number of lives lost, persons injured, damage to property and disruption of economic activity due to a particular natural phenomenon.

RISK ACCORDING TO UNESCO 1972

HAZARD

VULNERABILITY

VALUE

RISK




HAZARD SCHEME

HAZARDNATURAL

PROCESSES

PREDISPOSINGFACTORS

TRIGGERINGFACTORS

SUSCEPTIBILITY


SPA

CE

TIM

E

MAGNITUDERUNOFF

Heuristic, Statistic, Deterministic ….methods

Treshold value, ….




VULNERABILITY, VALUE SCHEME

VULNERABILITY

VALUE

HUMAN

ACTIVITIES

ECONOMIC

SOCIAL

STRUCTURES

INFRASTRUCTURES

PEOPLE

DIRECTINDIRECT




RISK SYSTEM

HAZARD

VULNERABILITY

VALUE

RISK

NATURAL

PROCESSES

HUMAN

ACTIVITIES

PREDISPOSINGFACTORS

TRIGGERINGFACTORS

SUSCEPTIBILITY


SPA

CE

TIM

E

ECONOMIC

SOCIAL

STRUCTURES

INFRASTRUCTURES

PEOPLE

DIRECTINDIRECT

MAGNITUDERUNOFF




Project AVI GNDCI-CNR

landslide inventory from 1918 to 1994

Landslide 32,000

Sites involved 21,000

Fatalities in the XX century 5,939

Average cost every year 1-2 billion €

The cost of Landslide Risk in Italy




The cost of Landslide Risk in USA – (USGS)

- landslide-related fatalities average from 25 to 50 per year, - direct and indirect economic costs to the nation range up to $3 billion per year.




The costs of landslides are increasing rapidly as lands susceptible to failure are developed for highways, housing, industry, and recreation. (USGS, LHP 2006-2010)




Increasing in the last 50 years of population; energy use; number of natural events; national internal production

(Bonachea 2006)

gross domestic product

population;

energy use;

number of natural events;




BUILDINGS

INFRASTRUCTURES

RECREATION

LAND USE

POPULATION GROWTH AND DEVELOPEMENT

HAZARDVULNERABILITY

VALUE

RISK

INCREASE

INCREASE

INCREASE

INCREASE

INCREASE

INCREASE




HAZARD RELATED TO HUMAN ACTIVITIES

HAZARD

VULNERABILITY

VALUE

RISK

NATURAL

PROCESSES

HUMAN

ACTIVITIES

PREDISPOSINGFACTORS

TRIGGERINGFACTORS

SUSCEPTIBILITY


SPA

CE

TIM

E

ECONOMIC

SOCIAL

STRUCTURES

INFRASTRUCTURES

PEOPLE

DIRECTINDIRECT

MAGNITUDERUNOFF




PLANNING

Planning land use can be related to three different conditions

1 - Maintenance with or without mitigation measure

2 - Change in the land use from “natural” to anthropic

3 - From anthropic use to “natural” in the cases related to abandoned mountain areas.




HAZARDNATURAL

PROCESSES

PREDISPOSINGFACTORS

TRIGGERINGFACTORS

SUSCEPTIBILITY


SPA

CE

TIM

E

MAGNITUDERUNOFF

HAZARD RELATED TO HUMAN ACTIVITIES




PREDISPOSING FACTORS RELATED TO HUMAN ACTIVITYHUMAN CAUSES•Excavation

•Loading

•Drawdown

•Land use change

•Water management

•Mining

•Quarrying

•Vibration

•Water leakage

•Deforestation

•Mining




PREDISPOSING FACTORS

Geological causes•Weak materials

•Sensitive materials

•Weathered materials

•Sheared materials

•Jointed or fissured materials

•Adversely orientated discontinuities

•Permeability contrasts

•Material contrasts

Morphological causes•Slope angle

•Uplift

•Rebound

•Fluvial erosion

•Wave erosion

•Glacial erosion

•Erosion of lateral margins

•Subterranean erosion

•Slope loading

•Vegetation change

NATURAL•Excavation

•Loading

•Drawdown

•Land use change

•Water management

•Mining

•Quarrying

•Vibration

•Water leakage

•Deforestation

•Mining

HUMAN




Climatic change: Patterns of linear global temperature trends over the period 1979 to 2005

Solid lines are multi-model global averages of surface warming (relative to 1980–1999) for the scenarios A2, A1B and B1, shown as continuations of the 20th century simulations

Figure SPM.5(IPCC, 2007)




HAZARDNATURAL

PROCESSES

PREDISPOSINGFACTORS

TRIGGERINGFACTORS

SUSCEPTIBILITY


SPA

CE

TIM

E

MAGNITUDERUNOFF

INFLUENCE OF GLOBAL CHANGE ON HAZARD

WARMING

INTENSITY




PermafrostLandslides and Slope StabilityPermafrostLandslides and Slope Stability canada geological survey

Any process which results in the exposure of icy sediment to thaw may induce a landslide. Thawing not only reduces cohesion but may also reduce frictional strength of the sediment especially if ice in excess of the sediment pore volume is present. The water produced by thaw must escape but until it does so, it carries the weight of the

slope sediments, decreasing the friction between soil particles. Landslides caused by elevated pore water pressures due to thawing ground ice are common in the Mackenzie Valley. Also, undercutting of river banks can result in

enough loading to overcome the cohesion of frozen sediments. Approximately 2,000 slides have been documented in the Mackenzie Valley, with a further 1,000 retrogressive thaw-flows identified in the Mackenzie Delta-Tuktoyaktuk

Peninsula area.

PermafrostLandslides and Slope Stability

Permafrost Landslides and Slope Stability

canada geological survey

GLOBAL CHANGE

WARMING IN PERMAFROST AREA

http://gsc.nrcan.gc.ca/permafrost/whatis_e.php#groundice




ZONATION EMERGENCY

RISK REDUCTION

-Where and when will landslides occur?

-How big will the landslides be? -How fast and how far will they

move? -What areas will the landslides

affect or damage? -How frequently do landslides

occur in a given locality?

FORECASTINGPREVENTION

HAZARD ASSESSMENT AND MITIGATION STRATEGIES

We have to solve these problems




VULNERABILITY

VALUE

HUMAN

ACTIVITIESECONOMIC

SOCIAL

STRUCTURES

INFRASTRUCTURES

PEOPLE

planning

Planning

evacuation

DIRECTINDIRECT

mitigation measures

Emergency management

ZONATION TO PLAN LANDSLIDE MITIGATION MEASURES

SPA

CE

TIME




EMERGENCY MANAGEMENT

THE GOAL IS TO REDUCE FATALITIES USING EARLY WARNING SYSTEM:

MONITORING SYSTEM-Triggering factors - Groundwater data from pressure sensors - Movement data from displacement sensors - Ground vibration from geophones.

GIS AND DATA BASE

MOBILE SYSTEM

DECISION SUPPORT SYSTEM




MONITORING SYSTEM TO FORECAST

HAZARDNATURAL

PROCESSES

PREDISPOSINGFACTORS

TRIGGERINGFACTORS

SUSCEPTIBILITY


SPA

CE

TIM

E

MAGNITUDERUNOFF

Heuristic, Statistic, Deterministic ….methods




EXAMPLE OF EMERGENCY MANAGEMENT

MOUNTAIN RISK PROJECT




SUSCEPTIBILITY MAP




HAZARD MAP ACCORDING TO REGIONE LOMBARDIA LAWS




DATA BASE VULNERABLE ELEMENTS

LINES

POLIGONS




VULNERABILITY MAPACCORDING TO REGIONE LOMBARDIA LAWS

POPULATION




RISK MATRIX ACCORDING TO REGIONE LOMBARDIA LAWS

VUN

ERA

BIL

ITY

HAZARD




RISK MAP ACCORDING TO REGIONE LOMBARDIA LAWS




RISK SCENARIO ACCORDING TO REGIONE LOMBARDIA LAWS




RISK SCENARIO ACCORDING TO REGIONE LOMBARDIA LAWS

ELEMENTS POTENTIALLY INVOLVED




EMERGENCY MANAGEMENT WORK FLOW

GIS AND DSS FOR A REAL TIME EMERGENCY MANAGEMENT

TRESHOLD COMMUNICATION

NORMAL CONDITION




EMERGENCY MANAGEMENT WORK FLOW

GIS AND DSS FOR A REAL TIME EMERGENCY MANAGEMENT

POPULATION EVACUATION

COMMUNICATION TO POPULATION

COMMUNICATION MANAGEMENT

CRISIS LOCAL UNIT ACTIVATION

EMERGENCY AREA ACTIVATION

POPULATION RETURN TO HOUSES

SUPPORT TO POPULATION

END OF EMERGENCY

EMERGENCY

PREVENTION ACTIVITYALARM PHASE




Tools to create a graphic workflow:BlocksConnectorsColorsText

DECISION SUPPORT SYSTEM

Block-related chart including documents, files, actions, contacts and entities involved




SOME CONSIDERATIONS

1- Risk assessment is difficult because the we need a system analysis.

2- Climatic change, human growth and social developement will increase hazard and risk.

3- Risk reduction is possible with planning and emergency management.

4- Information and communication are important tools because we must explain to stakeholders because research is necessary for a good planning.




SOME PROBLEMS

Which is the influence of man actvity on predisposing and triggering factors for hazard?

Are landslide risk costs sustenable?

If not more research or planning?

We must explain to stakeholders because research is necessary for a good planning.




THANKS FOR YOUR ATTENTION

Landslide hazard and risk: an integrated management of...

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